Evaluation of injection systems for open tubular liquid chromatography

Claessens, H.A.; Burcinová, Andrea; Cramers, C.A.M.G.; Mussche, P.; Tilburg, C.C.E. van

doi:10.1002/mcs.1220020309

Cited by 24 publications

(13 citation statements)

References 23 publications

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“…( 3) still provides a convenient representation of the minimal amount of hydrodynamic dispersion all injected peaks have been subjected to (V 2 ,inj,hydro) as well as of the variance contribution that increases with increasing injection volume (V 2 ,inj,vol). A similar differentiation between those two contributions was made by Claessens et al when investigating injection systems for open-tubular liquid chromatography [29], for normal and narrow bore column HPLC by Coq et al Coq [30] and Sanchez et al [31].…”

Section: Introductionmentioning

confidence: 53%

On-tubing fluorescence measurements of the band broadening of contemporary injectors in ultra-high performance liquid chromatography

Broeckhoven

Vanderlinden

Guillarme

et al. 2018

Journal of Chromatography A

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We report on a detailed study of the injection contribution to band broadening in contemporary UHPLC-instruments, using either flow-through needle or fixed loop injection (full loop). Using on-tubing fluorescence measurements at the outlet of the injector valve, very localized and undisturbed measurements were obtained. Varying both the flow rate and the injected volume allowed to split the injection variance (σ) in a volumetric component (related to the amount injected) and a hydrodynamic component (related to the flow rate). For the flow-through needle injector and for the small injection volumes (<2 μL) typically used in UHPLC, it was found that the volumetric contribution (i.e. the part of σ, that increases with increasing injection volume) is given by a value of σ = 0.8 to 1·V rather than by the value of 0.125 to 0.2·V that is normally assumed in literature. For the hydrodynamic contribution to σ (i..e, the part which remains present even for very small injection volumes), a clear increase in dispersion with flow rate is found, reaching a plateau around 0.8ml/min of 0.6 μL² or 1.2 μL² for the 75 μm and 120 μm needle seat capillaries respectively. The difference between both shows the clear advantage of using a low dispersion 75 μm injection needle seat capillary. For a loop-type injector operated in a full-loop mode, the increase in peak variance with the injection volume is much less pronounced, leading to a total injector variance given by σ = 0.34 μL² + 0.12·V over the entire range of investigated injection volumes of 1.1 μL up to 4.5 μL when using 120 μm or narrower ID loops. This expression was nearly completely independent of the flow rate. For larger ID sample loops, a clear increase of peak variance with flow rate at fixed injection volume was observed (σ increases with 20% for a 170 μm ID loop and with 70% for a 220 μm ID loop from 0.3 to 1 ml/min).

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Section: Introductionmentioning

confidence: 53%

On-tubing fluorescence measurements of the band broadening of contemporary injectors in ultra-high performance liquid chromatography

Broeckhoven

Vanderlinden

Guillarme

et al. 2018

Journal of Chromatography A

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“…Previous studies of injector design have shown that a good injection requires a narrow, low-volume plug of sample with no poorly swept flow paths [20,53,[58][59][60][61][62], which are explained more in the next section.…”

Section: Injector Contributionsmentioning

confidence: 99%

Measurement and Modeling of Extra-Column Effects Due to Injection and Connections in Capillary Liquid Chromatography

et al. 2015

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Abstract:As column volumes continue to decrease, extra-column band broadening has become an increasingly important consideration when determining column performance. Combined contributions due to the injector and connecting tubing in a capillary LC system were measured and found to be larger than expected by Taylor-Aris theory. Variance from sigma-type and tau-type broadening was isolated from eluted peaks using the Foley-Dorsey Exponentially Modified Gaussian peak fitting model and confirmed with computational fluid dynamics. It was found that the tau-type contributions were the main cause for the excessive broadening because of poorly-swept volumes at the connection between the injector and tubing. To reduce tau-type contributions (and peak tailing), a timed pinch mode could be used for analyte injection.

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“…Normalmente, tais volumes de injeção podem ser atingidos facilmente e com grande repetibilidade, utilizando válvulas comercialmente disponíveis. Caso se necessite de volumes de injeção menores que aqueles fornecidos pelas válvulas, pode-se empregar diversas técnicas de injeção descritas na literatura [59][60][61][62] . Atualmente, válvulas de até 4 nL podem ser encontradas comercialmente.…”

Section: Dispositivos De Introdução Da Amostraunclassified

Cromatografia Líquida Capilar1. Principais Características da Técnica

Coutinho¹,

Lanças²

2011

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Este trabalho de revisão crítica é parte de uma série cujo principal objetivo é apresentar e discutir as características mais relevantes da cromatografia líquida capilar (cLC). Dentre os vários aspectos cobertos neste trabalho, a revisão inclui o desenvolvimento, diferentes nomenclaturas propostas para a técnica, as principais vantagens, quando comparadas com a contrapartida denominada Cromatografia Líquida de Alta Eficiência (HPLC), e a instrumentação necessária para a operação no modo cLC. São também apresentadas e discutidas as principais razões pelas quais a cLC não é ainda uma técnica analítica de rotina.

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Evaluation of injection systems for open tubular liquid chromatography

Cited by 24 publications

References 23 publications

On-tubing fluorescence measurements of the band broadening of contemporary injectors in ultra-high performance liquid chromatography

On-tubing fluorescence measurements of the band broadening of contemporary injectors in ultra-high performance liquid chromatography

Measurement and Modeling of Extra-Column Effects Due to Injection and Connections in Capillary Liquid Chromatography

Cromatografia Líquida Capilar1. Principais Características da Técnica

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